9th International Symposium on
Non-CO2 Greenhouse Gases (NCGG9)

June 21-23, 2023, Amsterdam, The Netherlands



NCGG5 - 5th International Symposium on Non-CO2 Greenhouse Gases

Science, Reduction Policy and Implementation

June 30 - July 3, 2009, Wageningen, The Netherlands

Program, Presentations and Photos

Final report NCGG5

The final report on the conference is available now:

Final report NCGG5


The awarding of the Nobel prize for peace to the IPCC and Al Gore in 2007 acknowledges the importance of scientific progress in climate change research and recognizes our increasing concern about the possible consequences of climate change on the global environment and the human society.

The political debate on measures to reduce the emission of greenhouse gases is making progress. It focuses mainly on the reduction of CO2, which is a major, but not the only contributor to climate change. The major Non-CO2 Greenhouse Gases (Methane (CH4), Nitrous oxide (N2O) and Halocarbons) contribute, compared to CO2, 60 % of the radiative forcing. This presents attractive opportunities in emission reduction alternatives.

The Air Quality and Climate Change Section of the Netherlands Association of Environmental Professionals (VVM) organized its Fifth International Symposium on science, implementation and policy aspects of non-CO2 Greenhouse Gases (NCGG5) from June 30 to July 3, 2009, in Wageningen in The Netherlands. NCGG-5 addressed not only the role of non-CO2 greenhouse gases and aerosol in human-induced climate change, but also cost-effective options for reduction and its implementation in industry and society.

The symposium aimed to remove barriers beween policy and science and fosters the dialogue between scientists, engineers and officials in industry and government, which are all, though from a different perspective, involved in non-CO2 greenhouse gas issues.

Special NCGG session on recent global Methane increase

Is the recent increase of methane concentrations ending a temporary period of steady state?

In 2007 and 2008 the atmospheric methane concentration has been increasing again after a 6 year period of apparent steady state. At present it is still unclear whether the current increase is another temporary anomaly, like the one observed in 2004, or the start of a new period of methane increase. The focus of this session is on contemporary sources and sinks of methane, their tendencies in recent years, and plausible developments in the near future. Interesting areas include, for example, the response of natural sources to climate change and changes of anthropogenic emissions in response to regional changes in economical development, energy use, and agriculture. We welcome contributions from process modeling, analyses of atmospheric measurements and the construction of anthropogenic emission inventories.

Conference Chair

The Conference was co-chaired by Paul Crutzen, Scripps Institution for Oceanography and Bert Metz, Co-chairman of IPCC Working Group III.


The symposium will focus on the non-CO2 greenhouse gases; for that reason papers on general aspects of climate change or referring to CO2 alone, will not be accepted. 

A new issue in this conference series is the role of aerosols in climate change. The magnitude of radiative forcing of aerosols is equal, though of different sign, to all NCGGs together. A further study to its formation, abundance, future trends and interrelationship with NCGG emissions is therefore desired and relevant in this symposium.

Apart from the plenary Opening and Closing sessions, the symposium will be conducted in parallel sessions, focussing on the main themes: (i) Sources, sinks and inventories, (ii) Monitoring and modelling of atmospheric composition and (iii) Mitigation options and policy implementation. 

Theme 1: Sources, Sinks and Inventories

Data on sources and sinks are basic for understanding atmospheric composition and change in climate forcing, for emission inventories at different scales, and as input for models at varying scales. Topics for contributions could include:\

  • combustion in stationary and mobile sources: various emissions from fossil fuels, biofuels and biomass burning, including forest fires
  • industrial processes: fluorinated gases, nitrous oxide and methane
  • crop production: (N)-nutrient cycling in agriculture, and related emissions from soils and aquatic systems; methane from biomass; management systems
  • animal husbandry: methane from anaerobic processes in animals and manure
  • facility level inventories: farm scale and site specific budgets
  • natural sources and sinks
  • progress in emission inventories: national reports and their verification against atmospheric data
  • process-based high Tier emission models
  • primary aerosol emissions
  • verification of emissions and emission inventories and assessing uncertainties, taking into account possible new anthropogenic sources of NCGGs

Theme 2: Monitoring and Modelling of Atmospheric Composition 

There is a great need at various scales for reliable data for all greenhouse gases and other trace components which directly or indirectly affect the radiation balance, in order to improve the quality of emission inventories. Reports to be considered include the following topics:

  • atmospheric processes
  • relation between greenhouse gases and air pollution
  • primary and secondary aerosols and their influence on the radiative balance
  • monitoring of emissions and atmospheric composition from space
  • monitoring at background stations and high towers and from aircrafts
  • verification of emission fluxes and source strengths
  • atmospheric budgets of greenhouse gases and related biogeochemical cycles
  • modelling studies at varying scales, including inverse modelling

Theme 3: Mitigation Options, Reduction Policy and Implementation

NCGG-emissions have already been partly reduced through implementation of non-climate, climate and specific NCGG directed policies. However, there is still room for considerable improvement in industry and especially in agriculture. Implementation of cost-effective policies and measures as well as new technologies both in the public and private sectors will contribute to further accelerating and increasing NCGG-reduction. Reports and position papers could include the following topics on policy and implementation issues, including assessments of implementation programmes for NCGG-reduction and innovative approaches in policy implementations:

  • new developments in the national and international programmes
  • fluorinated gases: alternatives for specific gases like HFCs
  • the role of NCGGs in attaining national commitments for the first phase of the Kyoto Protocol
  • evaluation of national and international policies and measures to reduce air pollution and greenhouse gas emissions, identification of trade-offs
  • flexible instruments: Emission Tradings, Joint Implementation, Clean Development Mechanism and other policy options
  • development of integrated policies for air quality and climate change
  • inclusion of non-CO2 gases in the European Emissions Trading Scheme
  • economic analyses; scenario studies, including technology changes

NCGG5 is organized by:


Dutch Association of Environmental Professionals

In Cooperation with:

  • Dutch Ministry of Housing, Spatial Planning and the Environment
  • Australian Government, Department of the Environment and Heritage Australian Greenhouse Office
  • US Environmental Protection Agency
  • IEA Greenhous Gas R&D Programme
  • EFCA - European Federation of Clean Air and Environmental Protection Agency


Organizing Committee

  • Han van Dop, Utrecht University, co-ordinator
  • Herman Jan Wijnants, VVM, treasurer
  • Peter Builtjes, VVM
  • Charlotte Hoefsloot, VVM secretariatAndré van Amstel, WUR
  • Erik ter Avest, SenterNovem
  • Heleen de Coninck, ECN
  • Tinus Pulles, TNO
  • Peter van Velthoven, KNMI
  • Herman Walthaus, Netherlands Ministry of Housing, Spatial Planning and the Environment         
  • Rachel Heijne, VVM, director    

Conference Committee

  • Paul Crutzen, Scripps Institution for Oceanography, USA
  • Hennie Kelder, KNMI, The Netherlands
  • Adrian Leip, Joint Research Centre, Italy
  • Ingeborg Levin, Heidelberg University, Germany
  • Keith Lassey, NIWA, New Zealand
  • Javier Pérez Ramírez, ICREA, Spain
  • Thor Endre, ABB AS,Norway
  • Hink Perdok, Provimi, The Netherlands
  • Frank Raes, Joint Research Centre, Italy
  • Thomas Röckmann, IMAU, The Netherlands
  • Maarten Krol, WUR, The Netherlands
  • Peter van Velthoven, KNMI, The Netherlands
  • André van Amstel, WUR, The Netherlands
  • Bert Metz, European Climate Foundation, The Netherlands
  • Kornelis Blok, Utrecht University, The Netherlands
  • Jochen Harnisch, Ecofys, Germany
  • Heleen de Coninck, ECN, The Netherlands
  • Mack McFarland, Dupont Fluoroproducts, USA
  • David Ugalde, Australian Greenhouse Office, Australia
  • Paul Gunning, Environmental Protection Agency, USA
  • Mauricio Rosales, FAO, Italy
  • Tinus Pulles, TNO, The Netherlands
  • Henk van der Rhee, The Netherlands
  • Michael Rumberg, NobleCarbon, Germany
  • Han van Dop, secretary for theme 1 and 2
  • Erik ter Avest, secretary for theme 3

Latest News

Conference diner & excursion

Date: 01 June 2023
Conference Diner Have you already registered for the conference dinner on the first day of NCGG9?Join us at De Vergulden Eenhoorn on Wednesday 21s... Read more

To news archive

In cooperation with

Water Systems and Global Change Group, Wageningen University & Research
WIMEK Graduate School 


Symposium Secretariat

NCGG9 is organized by:


p/a UCo
2e Daalsedijk 6a
The Netherlands

T +31 (0)30 - 232 29 89
E eciffo.[antispam].@ncgg.info



Stichting MilCon (Foundation for Environmental Congresses, a separate legal entity that is linked to VVM) is responsible for the logistic and financial management of NCGG9. The contents of the symposium is the responsibility of VVM and its co-organisers. Logistic services for NCGG9 will be provided by the VVM-bureau.